Students, teachers and community members protest guns in response to the Stoneman Douglas High school shooting in Florida at the Colorado State Capitol on Wednesday, Feb. 21, 2018. Seventeen people were shot and killed during the school shooting on February 14, 2018.

WASHINGTON — Congress is leaving Washington in the aftermath of the latest mass shooting having done nothing to counteract systemic gun violence or improve school safety, with President Donald Trump’s extraordinary summit giving lawmakers little clarity on what policy measure he would ultimately endorse.

The Senate has been unable to untangle objections to a modest, relatively noncontroversial bill meant to improve the system for providing information to a federal background-check database. And without much guidance from the White House, Democrats and Republicans began laying out their proposals Thursday in an effort to prevent tragedies such as the Feb. 14 shooting at a Parkland, Florida, high school – but it’s far from clear how those measures can succeed without Trump’s backing.

Meanwhile, conservatives were apoplectic over Trump’s departure from GOP orthodoxy on guns, particularly his comment at Wednesday’s summit that firearms could be seized before their owners could be judged unfit to possess them.

“On the due process issue, that comment concerned me greatly,” said Sen. Steve Daines, R-Mont., otherwise a reliable Trump ally. “I disagree with the president on that issue. I think it’s a fundamental, constitutional Fourth Amendment issue.”

Several Republican lawmakers spoke up on social media and in other forums to push back on that notion, as well as Trump’s advocacy for stronger background checks and a higher minimum age for rifle purchases – taking it from 18 to 21, the current minimum age for handgun purchases.

In an interview, Rep. Thomas Massie, R-Ky., said he was disappointed that more of his Republican colleagues were not more forcefully rebutting Trump’s comments.

“There are not a majority of Republicans in the [House] who are going to follow Donald Trump over this cliff,” Massie said. “He should come back to Kentucky and do a rally with 30,000 people with [Sen.] Dianne Feinstein next to him giggling and [Sen.] John Cornyn to his left proposing gun control that would deprive veterans of their right to keep and bear arms. I don’t think that’s going to go over well in middle America.”

Massie was referring to the White House summit when Trump’s support for some gun controls left Feinstein, D-Calif., giddy and Cornyn, R-Texas, tight-lipped.

While numerous Republicans pushed back on Trump’s gun remarks – or, in some cases, tried to explain them away – Democrats tried to use the president’s comments to their advantage.

On Thursday, Senate Minority Leader Charles Schumer, D-N.Y., said his caucus would focus on passing a bill that would require the national criminal- background-check system to apply to firearms purchases made on the Internet or at gun shows; legislation allowing temporary protective orders to disarm people deemed to be a harm to themselves or others; and would be pushing for “a debate” – not necessarily passage – of a ban on assault-style weapons that expired during George W. Bush’s administration.

Each of the proposals has been backed by Trump in his recent public comments.

“Not every Republican is going to vote for this,” Schumer said. “But if the president works the room – meaning the Senate – we can get this done.”

National polling has shown wide support – more than 90 percent in some surveys – for bolstering the criminal-background-check system. A similar proposal was pushed by President Barack Obama and Democratic lawmakers in 2013 but failed to advance through Congress following the shootings at Sandy Hook Elementary School in Newtown, Connecticut.

Several states have enacted or are considering approving gun violence protective orders that allow family members or law enforcement officers to seek to temporarily block at-risk people from possessing or purchasing firearms – usually for up to three weeks.But there has been no rise in support forbanning assault-style weapons: Just 45 percent of independents and 29 percent of Republicans support doing so, according to a Washington Post-ABC News poll published last week. The poll found that 71 percent of Democrats support such a ban.

During a briefing Thursday, White House press secretary Sarah Huckabee Sanders did not elaborate on what Trump would like to see included in a bill but said he remains hopeful that lawmakers will pass strong legislation. She said Trump had spoken with Sen. Patrick Toomey, R-Pa., earlier Thursday about his background-checks legislation, adding that “discussions are still ongoing.”

“He does want Congress to come together and put forward a piece of legislation,” Sanders said.

Some senior lawmakers have begun investigating what went wrong at Marjory Stoneman Douglas High School in Florida, with Sen. Charles Grassley, R-Iowa, chairman of the Senate Judiciary Committee, announcing an oversight hearing that will examine law enforcement breakdowns surrounding the massacre that left 17 dead.

The leaders of the House Judiciary Committee and the House Oversight and Government Reform Committee sought and received a staff briefing from FBI leaders on their actions surrounding the shooting. But they have not publicly announced any further oversight activities.

Separately Thursday, House Minority Leader Nancy Pelosi, D-Calif., told reporters that she was “encouraged” by the White House meeting and “optimistic” that Trump would take action.

But Pelosi said Trump would have to persuade members of his party to set aside their long-standing objections to even narrow new restrictions on guns.

“We have to move forward, and not just some little bill,” she said. “It has to be substantial. It might not be an assault-weapons ban, but practically anything short of that is what we would expect.”

One prominent Republican, Sen. Marco Rubio, Fla., outlined legislation he could support in a Thursday floor speech – including improvements to school security, the creation of federal gun violence restraining orders allowing authorities to seize weapons from people found to pose a threat, and new penalties for “straw buyers” who purchase firearms intended for people who are prevented from buying guns themselves.

However, Rubio said the Parkland shooting did not result from gaps in the law but from a “massive multi-systemic failure involving federal, state and local authorities who failed to identify the threat [the gunman] posed and coordinate a response to stop him before he took action.”

“It is this failure which we should focus on by addressing the shortcomings and vulnerabilities in our current laws and policies,” he said.

The effects of the longest government shutdown in U.S. history continue to ripple across Colorado, with businesses near Rocky Mountain National Park reporting losses and furloughed federal workers applying for unemployment benefits.